The present invention relates to a back-flushable filter and also to a pressure-regulator. The invention is particularly useful when incorporating the pressure-regulator and the back-flushable filter in a single unitary device, and is therefore described below with respect to this application, but it will be appreciated that the pressure-regulator could also be used in other applications, and that the back-flushable filter could also be used without the pressure regulator.
Many types of back-flushable filters (namely those wherein the filter body is cleaned by applying the pressurized fluid to the downstream face of the filter body) have been developed and are now in use, particularly in water irrigation systems to remove the dirt particles from the irrigating water before they can reach the irrigating devices, such as sprinklers, drippers, and the like. Such filters usually have to be protected against an undue build-up of pressure within the filter housing, which could result in a dangerous explosion. For this reason, the filter line usually includes a separate pressure-regulator which acts to regulate the pressure within the filter housing, and/or to shut-off the input line from the filter housing should the pressure within the housing rise to a dangerous level. Such pressure-regulators, however, are quite expensive and frequently cost as much or more than the filter itself.